Microsoft held a 40 minute live demonstration of their free-to-play game making sim Project Spark, whose flexibility was shown off at E3 2013 when recreations of Limbo and Geometry Wars: Retro Evolved - among other games - where displayed.

The curious game wot makes games - Project Spark - is now open to beta registrations. The title was shown off during the Microsoft E3 conference, where players sculpt their own open world environments.

They can then fill those creations with settlements and NPCs, before dabbling in some scripted quests and the like. The selling point is sharing these 'games' and even remixing.